Velocity modulation tube



Sept. 9, 1952 TOURATQN ETAL 2,610,306

VELOCITY MODULATION TUBE,

Filed June 14, 1948 F/Gl. F/GZ.

Inventor E. TOURATON C.DUMOUSS EAU A Home y Patented Sept. 9, i952VELOCITY MODULATIONTJTUBE Emile Touraton and Claude Dumousseau, Paris,France, assignors to International Standard ration of Delaware ElectricCorporation, New York, N. Y., a. corpo- Appl cation June 14,1948,SerialNo. 32,975 V In France June 14, 1947 The present invention relatestovelocity modulation tubes and in particular to such tubes used asamplifiers forultra high frequencies.

According to features of the invention the velocity modulation tubeaccording to the invention comprises two units and two electron beams.The electrons of the first beam are velocity modulatedin a firstmodulation resonator and excite a catcher resonator. This catcherresonator operates as a modulation resonator for a second electron beamwith a modulation factor higher than that of the first modulationresonator, and the electrons of this second beam excite "a secondcatcher resonator.

With this double modulation process it is'possible to secure a higheramplification factor for the same output power and the tube may beconsidered as comprising a power amplifier preceded by a. pre-amplifier.

The above 'mentioned'and other features and objects of this inventionwill become more apparent and the invention itself, though notnecessarily defined by said features and objects, will be :bestunderstood byreference to the following description of an embodiment ofthe invention taken in connection with the accompanying drawingswherein:

Fig.1 shows a first embodiment, and

Fig. 2 shows a second embodiment of the inventiona' Referring now toFig. 1 this figure'shows a first embodiment comprising a, first cathodeI whose potential is chosen asia reference potential for the remainderof the description, a first concentrating or Wehnelt electrode! at apotential of for instance 100 volts, a first modulating cavity resonator3 at a high potential, for'instance 6000 volts, a drift electrode 4 atalow potential, for instance +50 volts, in which 'theelectronscollectrinto bunches.

This drift electrode 4 is provided with two auxiliary; electrodes '5 and6 of conical shape intended to focus the electron beam and which arebrought'respectively to potentials of +3000 volts for electrode and +500volts for'electrode 6, for example. r

The low intensity electron beam 8 from cathode -l fiows through thefirst part of the tube including'za second "cavity resonator 1 to whichit transfers high frequency energy.

After the drift electrode is provided a second circul r cathode. 9 at apotential. of, for instance +6. 0 volts, which is provided with aWehnelt electrode in at a. potential 100 volts lower than the: cathode,i. e. +500'volts.

a 12 Claims. (01. 315-6) The two electron beams a and l l flow throughresonator 1 which operates as a catcher resonator for the first beam 8and ass. modulation resonatorfor the second beam II. The resonator 1,excited by beam 8 after the bunching of the-electrons in the driftelectrode 4, velocity modulates the second beam and the tube works as anamplifier in which the second beam ll works in a manner similarto-beam*8 in'the firstpartof the tube structure. A second drift electrode I2 isprovided to this effect following resonator i brought to a relativelylowpotential of for instance +1000 volts. in which the electrons areslowed down and group themselves into bunches. The potential and shapeof'thevarious electrodes are so chosen that beam'ii be focalised atthelevel of the second catcher resonator I 3. On the contrary, theelectrons of'the-first'beam 8 are collected by the third resonator I3;The first beam is of low intensity and may be'collected by the highpotential resonator. l3 .without decreasing substantialythe overallefliciency of the tube.

Since the angular opening of the second beam II is larger it is,.on thecontrary,'focalised in the opening of the. third resonator l3 brought toa potential of +7000 volts for instance, and which operates as a catcherresonator. The beam finally reaches a collector electrode 14 at arelatively low potential, for instance 2000 volts. A reflector l5 at anul or negative potential, de fiects the beam ll towardcollectorM.

Fig. 2 shows another embodiment of the invention comprising, as in thefirst embodiment, a cathode I1, a Wehnelt electrode [8 at a negativepotential, for instance volts, a first resonator at a potential of +6000volts for instance, a first drift, electrode 20 at a low potentialof,for instance, 200 vol provided with two auxiliary electrodes 2| and 22brought to the same P0111611?- tial of'200 volts for instance, whichdirect the beam intothe drift tube 20;

Inside tube 20 is provideda second annular cathode 23 at a potential of,for instance 300 volts, which'generates a, second conical beam 24 with asmaller angle than the first beam 25.

The two beams fiow through the second resonator 26 which works as acatcher resonator for the first beam and as modulation resonator for thesecond beam. y

The second beam "24 flows through a second drift electrode 21 at arelatively low potential, 1000 volts forinstance, in which the electronsare slowed'do-wn and groupedinto bunches. The beam then fiows through acatcher resonator 28 ata. potential of, for instance, +7000 voltsresonator the first beam cannot penetrate into the second driftelectrode and is collected by the said second electrode which is at ahigh potensecond resonator for collecting the electrons from said secondbeam.

4. A velocity modulation tube, comprising a first electron gun forprojecting a first beam along a beam path, a first cavity resonatoradjacent .said first gun and about said beam path for velocitymodulating said first beam, a second electron gun disposed in said beampath adjacent and beyond said first resonator for projecting a secondbeam along said beam path, said first gun having means for focussingsaid first beam past tial, the overall efliciency is however notsubstantially affected on account, of tensity of this first beam.

The tube which has just been described conthe low' in- 1 said secondgun, -a second cavity resonator ad- --jacent said, second gun and aboutsaid beam path for extracting energy from said first beam stitutes anoutput amplifier preceded by a preamplifier in which the modulationresonator of lustration it should be understood that'variousmodifications and adaptations thereof may be made within the spirit ofthe invention as set forth in the appended claims. u

What we claim is: f

l. A velocity modulation tube, comprising a first electron gunforprojecting a first-beam along a beam path, a first cavity resonatoradjacent said first gun and about said beam path for velocity modulatingsaid first beam, a second electron gun adjacent and beyond said firstresonator for projecting a second beam along said beam path,'a secondcavity resonator adjacent said second gun and about said beam path forextracting energy from said first beam and for velocity modulating saidsecond beam, and a third cavity resonator adjacent said second resonatorand about said beam path for extracting energy from said second beam. 11

2. A velocity modulation tube, comprising a first electron gun forprojecting a first beam along a beam path, a first cavity resonatoradjacent said first gun and about said beam path for velocity modulatingsaid first'beam, a second electron gun adjacent and beyond said firstresonator and about said beam path for projecting a second beam alongsaid beam path, said first gun having means for focussing said firstbeam to pass through said second gun, a second cavity resonator adjacentsaid second gun and about said beam path for extracting energy from saidfirst beam and for velocity modulating said second beam, a drift tubeadjacent said secondcavity resonator andabout said beam path forstopping said first beam, and a third cavity resonator adjacent saiddrift tube and about said beam path for extracting energy from saidsecond beam.

3. A velocity modulation tube according to claim 2 further comprisingmeans by which a potential difference may be applied between said drifttube and said second cavity resonator to cause the electrons in saidfirst beam to be collected by said second cavity resonator beforepassage therethrough and means beyond said and for velocity modulatingsaid second beam, a driftspace defining means adjacent said secondresonator for stopping said first beam, and a third cavity resonatoradjacent said drift space 'de'fining' means and about said beam path forextracting energy from said second beam.

5. A velocity modulation tube according to claim 4 further comprisingmeans by which a potential may be applied to said-drift space definingmeans to reflect said first beam for collection by said second resonatorand means adjacent said third resonator for collecting said secondbeam.- j

'6. A velocity modulation tube, comprising a first velocity modulationstructure having a modulating cavity resonator and a catcher cavityresonator, a first electron gun'for projecting a first beam of electronsthrough said resonators and means adjacent said catcher resonator forcollecting electrons in said first beam, and a second velocity-modulation structure including a second electron. gun'mounted betweensaid modulating and catcher resonators of said first structure forprojecting a second electron beam through said catcher resonator andfurther including a second catcher cavity resonator adj acent said firstbeam collecting meansand about the path of said second beam.

'7. A velocity modulation tube comprising a first velocity modulationstructure having a modulating cavity resonator and a catcher cavityresonator, a second velocity modulation structure, the catcher cavityresonator of said first structure constituting a modulating cavityresonator for said second structure, said second structure having acatcher resonator, a first electron gun disposed adjacent the modulatingcavity resonator of said first velocity modulating structure forprojecting an electron beam through said first velocity modulationstructure and a second electron gun disposed between the modulating andcatcher cavity resonators of said first velocity modulating structurefor projecting an electron beam through the said second velocitymodulation structure.

8. A velocity modulation tube comprising a first electron beam source, afirst velocity modulation structure having a modulating and a catcherresonator disposed in alignment with said first beam source, a firstmeans for focusing the electron beam ofsaid first source through saidcavity resonators, a second electron beam source disposed between themodulating and catcher resonators of said first velocity modulatingstructure, a second velocity modulation structure having a catcherresonator, a second means for focusing the electron beam of said secondsource throughthe catcher resonator of said first modulation structurethence through the catcher resonator of said second structure.

9. In a velocity modulation tube, a first electron beam source, a secondelectron beam source disposed in tandem relation with respect to saidfirst beam source for beam travel along a common path, means to modulatesaid first beam, means disposed adjacent said common path to transferthe modulation of said first beam to said second beam, and meansadjacent the path of said second beam to receive modulated energy fromsaid second beam.

10; In a velocity modulation tube according to claim 9, wherein themeans to transfer the modulation of said first beam to said second beamincludes a cavity resonator disposed adjacent the paths of both saidfirst and said second beams.

11. In a velocity modulation tube according to claim-9, wherein each ofthe three means recited therein includes a cavity resonator.

6 12; In a velocity modulation tube according to claim 11 furtherincluding focusing electrodes to direct said first beam through thefirst and second resonators only and to direct the sec- 0nd beam throughthe second and third resonators only.

EMILE TOURATON.

CLAUDE DUMOUSSEAU.

REFERENCES CITED 'The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

